This invention relates to the art of waveform generators and more specifically to a waveform generator for generating an analog signal based on digitized representations of the waveform to be generated.
Waveform generators are known in the art. Such an example is found in the U.S. Pat. No. to J. A. Naive, 3,386,039. This patent discloses an analog system including a linear integrator and a switching circuit to produce a triangular waveform or square waveform or a sine waveform.
Another example of a prior art waveform generator is disclosed in U.S. Pat. No. to Butler, 3,689,914. In this approach, a digital signal is applied to an accumulator which accumulates and stores digital signals with the output of the accumulator being applied to a digital-to-analog converter to provide an analog output signal. The output signal takes the form of a triangular wave or a square wave.
With the advent of computer technology, waveform generators have included computer assistance. One example of this is found in the U.S. Pat. No. to Bloomer, 3,694,632. Here a matrix of digital differential analyzer (D.D.A.) integrators are employed in conjunction with a computer. The computer interconnects the integrators within a matrix for generating digital patterns representative of a particular waveform which is then converted by an digital-to-analog converter.
A more recent example of the prior art takes the form of the U.S. Pat. No. to Winkler, 4,168,527. This patent discloses a processor controlled waveform generator wherein a plurality of digitized waveforms are stored in a memory. Under processor control, these digitized words are supplied to a holding register which is provided to minimize skewing effects into an analog-to-digital converter.
Another example of recent prior art takes the form of a waveform generator available from Wavetek of San Diego, Calif. and known as their model 175 arbitrary waveform generator. This is described and illustrated in their instruction manual, Instrument Release D-2, 1980, Manual Revision, May, 1980. The Wavetek model 175 waveform generator is similar to that illustrated and described in the Winkler patent, supra. The model 175 waveform generator employs a memory for storing digitized waveforms and is on line with a processor. The processor selects a digitized waveform from the memory. Each data word obtained from the memory is supplied to a digital-to-analog converter for generating the analog version of the waveform. Additionally, under processor control, the memory is addressed from a programmed start address to a programmed stop address within a block of memory locations containing the digitized waveform. This generator has a continuous mode of operation or a triggered mode of operation, having a programmed number of cycles for generating the waveform.